Roll assembly

ABSTRACT

A roll assembly for receiving elongated material passing thereover comprises a pair of spaced rolls mounted on shafts which are skewed at an angle with respect to each other. The rolls are arranged to accept the material for travel over its ideal path wherein the points at which the material enters and leaves each roll are coarcuate with the path being disposed on each roll along lines of contact with that roll and with the lines of contact of each roll being disposed upon the surface of an imaginary sphere and each such line of contact being coplanar with the path of the material as it approaches and leaves said line of contact.

United States Patent [191 Laird Jan. 29, 1974 1 ROLL ASSEMBLY Primary Examiner-Richard A. Schacher [76] Inventor: J. Packard Laird, 915 Center Rd., Attorney A or Flrm connony and Hutz Wilmington, Del. 19807 221' Filed: Aug. 18, 1971 [57] Sl A roll assembly for receiving elongated material passl PP 172,635 ing thereover comprises a pair of spaced rolls mounted on shafts which are skewed at an angle with 52 US. Cl 165/65, 62/5, 165/89, respect other- The 8 Prearranged P 226/118, 254 1 3 the material for travel over its ideal path wherein the 51 Int. Cl F28d 11/02 points at which the material enters and leaves each 53 Field f g h zjg/ g; T9; z5'4l'j'g3' roll are coarcuate with the path being disposed on 62/5; 165/89 each roll along lines of contact with that roll and with the lines of contact of each roll being disposed upon [56] References Cited the surface of an imaginary sphere and each such line UNITED STATES PATENTS of contact being coplanar with the path of the material v as it approaches and leaves said line of contact. 929,508 7/1909 Smith 254/184 3,695,396 10/1972 1 Jones 254/175.5 X 20 Claims, 7 Drawing Figures I: Healad Gals I l 641 Hilsclp 143 T ube K 52 5 r WJPZex 10B Compressor T ube g0:

Cooled Gas L PATENTEDJAN 2 1w 3; 788391 SHEEI 2 OF 2 ROLL ASSEMBLY BACKGROUND OF INVENTION This invention relates to a roll assembly and more particularly to such an assembly which is adapted for use in drawing yarn. Various arrangements exist for drawing yarn. For example in the conventional drawroll assembly two cylindrical rolls are mounted with their axes of rotation slightly skewed relative to each other. The rolls are power driven in the same rotational sense at essentially equal surface speeds. Yarn is threaded around the two rolls so that it travels several times around the pair of rolls, passing from one roll to the next. The effect of the skew angle between the roll .axes is to cause successive wraps of the yarn around each roll to be offset from each other so that the yarn does not wrap on itself. This advancing of the yarn in a spiral fashion is a consequence of the skew angle. However, the path of the yarn is influenced by the fact that at each point where the yarn leaves a roll, it leaves in a non-ideal manner which is later discussed. The ef-- SUMMARY OF INVENTION An object of this invention is to provide a roll assembly which overcomes the disadvantages of conventional assemblies.

A further object of this invention is to provide such a roll assembly wherein the yarn or other elongated material travels along its ideal path.

A still further object of this invention is to provide such an arrangement which may be adapted to purposes other than drawing-yarn.

In accordance with this invention a roll assembly for receiving elongated material passing thereover comprises a pair of spaced rolls mounted on shafts which are skewed at an angle with respect to each other. The rolls are arranged to accept the material for travel over its ideal path wherein the points at which the material enters and leaves each roll are coarcuate with the path being disposed on each roll along lines of contact with its roll and with the lines of contact of each roll being disposed upon the surface of an imaginary sphere and each line of contact being coplanar with the path of the material as it approaches and leaves said line of contact.

In a preferred form of this invention the lines of contact of each roll are parallel to each other and are at an angle to the parallel lines of contact of the other roll. As used in this specification the term parallel" when referring to lines of contact, grooves, etc. means parallel in the sense of being disposed in planes which are parallel to each other.

Each roll may be a sphere having parallel grooves corresponding to its lines of contact or the rolls may be of stepped construction with a line of contact disposed on a step. In this respect the rolls may be of identical step construction with lines of contact being on alternate steps of the rolls or the rolls may be of comple mefitary stepped construction with a line of contact on each step.

2 Means may be provided on each roll for heating the stretch half of the roll and cooling the relaxation half thereof.

THE DRAWINGS FIG. I is a schematic view indicating the ideal path that is achieved in accordance with this invention;

FIG. 2 is a side elevation view of a roll assembly in accordance with this invention with ancillary equipment schematically illustrated therein;

FIG. 3 is a top plan view of the assembly shown in FIG. 2;

FIG. 4 is a side elevation view of an alternative roll assembly in accordance with this invention;

FIG. 5 is a top plan view of the assembly shown in FIG.'4;

FIG. 6 is a side elevation view of a further roll assembly in accordance with this invention; and

I DETAILED DESCRIPTION This invention provides a pair of rolls whereby the elongated material such as yarn would travel along an ideal path. In this respect when yarn travels over a rotating pulley, the axis of the yarn as it approaches the pulley and the axis of the yarn after it leaves the pulley both lie in the plane of the'pulley. The term plane of the pulley refers to the plane defined by the axis of the yarn while it is in contact with the pulley. If the yarn travel is ideal the pulley can be grooved, flat or slightly crowned. When the yarn travel is ideal there is no scuffing of the yarn although of course the yarn which enters the groove of a grooved pulley might touch the edge of the groove even under ideal conditions. Conversely, if the travel is non-ideal, scuffing will occur and where there is non-ideal travel as the yarn enters the pulley a travel. As indicated'therein a pair of rolls are provided with the lower roll disposed along its axis A and the upper roll along its axis B with axes A and B skewed with respect to each'other. The yarn first contacts the lower roll at point 11 and travels along the surface of that roll along the path designated A until the point 13 is reached. The path A, is perpendicular to axis A. The yarn then travels straight upwardly and contacts the upper roll at the point directly above point 13 of the lower roll. The yarn then travels overa portion of the upper roll along the path B, which is perpendicular to axis B until the point 15 is reached. The yarn then leaves the upper roll and travels downwardly until it.

path direction occurring at points 17, 19, 21 and 23.

The line of intersection of the vertical planes containing axes A and B is indicated by the letter C. As is apparent from FIG. 1 the points at which the yarn enters and leaves each roll are coarcuate. Additionally, the lines of contact on the surface of each roll are arranged so as to be disposed upon the surface of an imaginary sphere. As is further apparent from FIG. 1 the maximum path traveled by the yarn along any path is A,, which intersects line C. Additionally, the paths of travel progressively increase in length from the point 11 where the yarn contacts the first roll until path A and 3 progressively decrease in length thereafter. In this manner the yarn is stretched until path A and is relaxed thereafter. Such stretching and relaxation is particularly useful in drawing yarn to for example molecularly orientate the filaments and then permit them to relax.

Care is chosen in selectingthe location of the yarn paths. For example referring again to Fig. 1 where grooves are provided for the yarn path (as illustrated in FIG. 2), the diameter of any groove i would be determined by the equation D, D COS (i a), where D,, is the diameter of the imaginary sphere upon which the grooves lie and i is the number of the groove counting outward from groove D where i O and with the polarity of i being determined as positive and negative as illustrated in FIG. I. The angle a is the skew angle in degrees. The location of any groove i with respect to point C would be defined by X 1/2 D SIN Although FIG. 1 illustrates the maximum path length being disposed at the diameter of the imagninary sphere, it is not necessary to select this location for the maximum path length. Thus the more general mathematical definition of groove diameter is given by the equation D, D COS (ia b) where b is an angle in degrees and i is the number of the groove counting outward from a groove called D, D COS (b). The location of any groove 1' with respect to point C would be-defined in the general case by X, l/2 D SIN (ia b). Given the maximum pulley diameter then only a single design parameter, the skew angle, is necessary to determine the location of each path and the diameter of its groove. In the illustrated embodiments the skew angle a is l5 for convenience of illustration. In practice, however, a skew angle of 37 is more preferable.

The number of grooves which could be puton a single roll would be limited only by the accuracy of alignment of the rolls and the clearance which must be maintained between successive wraps of yarn. Accordingly, the stretching and relaxation of the yarn could be accomplished in as fine steps as desired. It is further noted that the yarn can be introduced into the yarn roll assembly at any pulley location which would provide an increase and can exit at any pulley location thus providing an opportunity for choice in the use or non-use of relaxation and the amount thereof. For a given roll design wherein there is a specific maximum pulley diameter D and skew angle and there is proper alignment, the path of the yarn is completely determined by establishing the line of entry forthe yarn onto the first pulley and providing the desired number of wraps. The line of entry must be in the plane of the first pulley and several path for the yarn to travel, might incorporate other advantageous features. For example as later described with respect to FIG. 2, it is possible to heat one-half of each of the rolls and cool the other half thereby providing hot drawing and cooled -relaxation of the same assembly. Referring now to FIG. 2 the cooling and heating might be accomplished in any suitable manner. In the illustrated embodiment a Hilsch vortex tube 62 is schematically shown along the lines of US. Pat. No. 1,952,281. This arrangement includes an air compressor for vortex tube 62 whereby the hot gas from the vortex tube travels along lines 64, 66 to the entrance side of rolls 12A and 108. The cold gas from the vortex tube travels along-lines 70, 72 to the exit side of rolls 12A and 108. It is to be understood that illustration of the specific means for heating and cooling is not intended to be limiting and other suitable means such as thermoelectric devices may be used. It is also to be understood that such temperature control may be incorporated in all of the embodiments of this invention. It is to be further understood that it is within the concepts of this invention to heat and/or cool all or part 'of any roll.

A distinctive feature of the inventive draw roll assembly is that it lends itself well to yarn pulling contrast to yarn drawing. For example where a pair of rolls are intended to transport yarn in a positive manner a slight stretch of the yarn upon entering the assembly establishes the ability of the rolls to pull, while a mild relaxation relieves the tension before the yarn leaves the roll assembly. In such a case small diameter pulley would not be used.

A further advantageous feature of this invention is that the roll assembly lends itself to yarn tension buildup or letdown. In this respect for the tension to be built-up on a running thread line the yarn must be stretched. Passing the yarn only over those pulleys wherein the grooves progressively increase in diameter from the entrance end to point C (i.e., those paths designed by the positive subscript in the drawings) would accomplish this stretch. Conversely, tension letdown would be accomplished by running over pulleys wherein the paths are designated as negative subscripts. Thus the roll assembly is capable of functioning as a separator between portions of yarn handling operation which must operate at different tension levels.v

The specific form which the rolls may take may vary in accordace with this invention. As illustrated in FIGS. 2-3 rolls 10B and 12A are each substantially spherical with grooves being provided on the idea] yarn path. Roll 108 is mounted for rotation on its shaft 14B while roll 12A is mounted for rotation on its shaft 16A. In the illustrated embodiments the yarn is intended to leave the rolls after being only slightly relaxed. Accordingly,

in such an embodiment it is not necessary that spherical segments at the left hand ends'of the rolls be provided. It is further noted that in FIGS. 2-3, since the rolls are tory. It is possible however, to manufacture the rolls non-identically with respect to the grooves so that grooves would be provided only where the yarn is intended to actually travel. 7

FIGS. 4-5 show a further arrangement which incorporates the novel concepts of this invention. As indicated therein rolls 30B and 32A are provided in the form of a series of flat pulleys mounted on shaft 348 and 36A, respectively. The composite structure thus in effect is stepped. However, the ideal path taken by the yarn is such that the contact points are coarcuate and the lines of contact of each roll are disposed upon a surface of an imaginary sphere. It is noted that the yarn path includes the same letter sufiix and subscript for which had construction.

In the arrangement shown in FIGS. 4-5 rolls 30B and 32A are identically formed. Thus alternate steps are not used in the ideal path. FIGS. 6-7, however, show the pair of complementary shaped rolls 50B and 52A which correspond to those illustrated in FIGS. 4-5 wherein the stepped construction is provided soley to accommodate the ideal path so that each step is actually used. Thus rolls 50B and 52A differ in construction from each other.

Satisfactory use of the roll assembly would depend upon the proper fabrication of the rolls and the alignment thereof. Initial alignment of the rolls and subsequent check thereof can be provided by providing a precise flat, with a dimple in the center, on the outboard end of each roll. This flat would then be used to check for angular alignment, axial position and angular wobble in the conventional manner.

The concepts of this invention may be applied in manners other than as previously described and illus trated. For example the elongated material need not be yarn but can be a belt, webb or other flat bendable surface so long at it is capable of being twisted by the amount of the skew angle. Additionally, the direction of travel of the thread line can be reversed if desired thus permitting bidirectionality of motion. Moreover, it

I is possible to change the separation between a given set of rolls even during operation. Thus the rolls can be either close together or remote from each otherand the separation can be changed without affect on the path of the thread line over the surface of the rolls It is also possible to utilize the roll assembly for processing multiple ends running parallel and for process of tows. A further possibility is that the assembly lends itself for either positive drive of the pulleys or the pulleys may rotate freely on the shafts.

As previously indicated the novel roll assembly may be used for processing a multiple end thread line in which a plurality of single threads run side by side. The separation between the parallel threads will decrease on each successive path over the rolls as with the conventional rolls. With the inventive rolls the detrimental affects of this decrease or closing up of the clearance between the filaments are minimized in three ways.

be driven each with comparable power and each of which must stand up against comparable forces from theyam.

The concepts of this invention may even be applied as a driving means mounted in an assembly to serve as a capstan. In application of the roll assembly for this purpose the pulleys would be grooved or shaped to give a good bite on the rope or' cable being transported. Such an assembly could involve boat anchors, cranes, derricks, cable cars or the like. The assembly could be placed between a cable wind up and the working load would separate the functions of pulling and storing, thus improving the performances of the machine in which it is used. The principles of this invention can thereby be applied to transmission of power by rope or by belt. Moreover power can be put in by one assembly and taken out by a second assembly with a rope or belt passing between the two assemblies.

As also previously pointed out the novel roll assembly may be formed as asuccession of pulleys fastened together to form one stepped roll with two such rolls comprising the assembly. In the illustrated embodiments of FIGS. 4-7 these rolls were power driven. When, however, the pulleys are free to rotate independently, additional uses may be put to the assembly. For example such an independently rotating pulley assembly would provide improved performance of tackle and hoists. In this respect a conventional two-block tackle does not provide ideal travel of the ropes over the pulleys especially when the blocks come together in the two block position. The inventive assembly, however, provides ideal travel. The concepts of this inven- First the skew angle is less with the inventive rolls,

being only for example 3-7. This reduces the closing up. Second none of the threads is displaced more than a fraction of an inch from the ideal path toward which they all move. This also reduces the closing up. Third because scuffing is virtually eliminated with the inventive roll assembly, the threads can run closer than in the case of conventional draw rolls thus enhancing the preceding affects.

Where the roll assembly is used for processing a tow, the bundle is maintained intact during its successive passage over the rolls for the reasons indicated above with respect to the multiple end threads. Specifically the inventive rolls permit the drawing of a tow with a single pair of large rolls involving only two shafts, having non-critical separation, but mounted to withstand very large forces from the yarn and-which would require large driving power. This is in contrast to conventional processing in which many heavy duty rolls must tion may likewise be applied to a chain hoist. Similarly, the use of a roller chain or wide flat belting in a hoisting apparatus employing the bock-and-tackle principle could be utilized to mechanical advantage. With conventional arrangements the non-ideal travel onto or off of the pulley requires sideways bending of the roller chain or belt thereby placing the entire tensile load along one side of the chain or belt. With the novel arrangement this difficulty is eliminated and the tensile forces are maintained evenly on both sides which opens up the possibility for new hoist designs based on belting, webbing, roller chains or the like.

As is apparent the novel roll assembly which provides an ideal path of travel can be advantageously used in a wide variety of ways while imparting the benefits of this invention.

What is claimed is:

1. A roll assembly for receiving elongated material passing thereover comprising a pair of spaced rolls, each of said rolls being mounted on a shaft, said shafts being skewed at an angle with respect to each other, said rolls being arranged to accept the material for traveling over its ideal path wherein the points at which the material makes and breaks contact with each roll are coarcuate, the path sements being disposed on each roll along lines of contact with its roll, and the lines of contact of each roll being disposed upon the surface of an imaginary sphere.

2. The assembly of claim 1 wherein the lines of contact of each roll are parallel to eachother and are 3. The assembly of claim 2 wherein each roll increases and then decreases in diameter.

4. The assembly of claim 3 wherein each roll is at least a portion of a sphere having parallel grooves corresponding to its lines of contact.

5. The assembly of claim 3 wherein each roll is of a stepped construction and each line of contact being disposed on a step.

6. The assembly of claim 5 wherein the rolls are of identical stepped construction, and each roll having alternate steps with no lines of contact thereon.

7. The assembly of claim 5 wherein the rolls are of complementary stepped construction and a line of contact being on each step.

8. The assembly of claim 5 wherein each roll comprises a plurality of individual pulleys of different diameters to form said stepped construction.

9. The assembly of claim 3 wherein means are provided for heating the stretch half and cooling the relaxation half of each roll.

10. The assembly of claim 3 includingtemperature control means for adjusting the temperature of at least a portion of at least one roll.

11. The assembly of claim 1 wherein said shafts are skewed at an angle of about 3 to 7 degrees with respect to each other.

12. The assembly of claim I wherein each'of said rolls is a roll sub-assembly, and each roll sub-assembly comprising a plurality of individual pulleys freely mounted coaxially on its shaft.

13. The assembly of claim 12 wherein the lines of contact of each roll are parallel to each other and are at the skew angle to the parallel lines of contact of the other roll.

14. The assembly of claim 13 wherein each roll increases and then decreases in diameter.

15. The assembly of claim 14 wherein each roll is of a stepped construction and each line of contact being disposed on a step.

16. The assembly of claim 15 wherein the rolls are of identical stepped construction, and each roll having alternate steps with no lines of contact thereon.

17. The assembly of claim 15 wherein the rolls are of complementary stepped construction and a line of contact being on each step.

18. The assembly of claim 14 wherein means are provided for heating the stretch half and cooling the relaxation half of each roll.

19. The assembly of claim 14 including temperature control means for adjusting the temperature of at least a portion of at least one roll.

, 20. The assembly of claim 12 wherein said shafts are skewed at an angle of about 3 to 7 degrees with respect to each other. 

1. A roll assembly for receiving elongated material passing thereover comprising a pair of spaced rolls, each of said rolls being mounted on a shaft, said shafts being skewed at an angle with respect to each other, said rolls being arranged to accept the material for traveling over its ideal path wherein the points at which the material makes and breaks contact with each roll are coarcuate, the path sements being disposed on each roll along lines of contact with its roll, and the lines of contact of each roll being disposed upon the surface of an imaginary sphere.
 2. The assembly of claim 1 wherein the lines of contact of each roll are parallel to each other and are at the skew angle to the parallel lines of contact of the other roll.
 3. The assembly of claim 2 wherein each roll increases and then decreases in diameter.
 4. The assembly of claim 3 wherein each roll is at least a portion of a sphere having parallel grooves corresponding to its lines of contact.
 5. The assembly of claim 3 wherein each roll is of a stepped construction and each line of contact being disposed on a step.
 6. The assembly of claim 5 wherein the rolls are of identical stepped construction, and each roll having alternate steps with no lines of contact thereon.
 7. The assembly of claim 5 wherein the rolls are of complementary stepped construction and a line of contact being on each step.
 8. The assembly of claim 5 wherein each roll comprises a plurality of individual pulleys of different diameters to form said stepped construction.
 9. The assembly of claim 3 wherein means are provided for heating the stretch half and cooling the relaxation half of each roll.
 10. The assembly of claim 3 including temperature control means for adjusting the temperature of at least a portion of at least one roll.
 11. The assembly of claim 1 wherein said shafts are skewed at an angle of about 3 to 7 degrees with respect to each other.
 12. The assembly of claim 1 wherein each of said rolls is a roll sub-assembly, and each roll sub-assembly comprising a plurality of individual pulleys freely mounted coaxially on its shaft.
 13. The assembly of claim 12 wherein the lines of contact of each roll are parallel to each other and are at the skew angle to the parallel lines of contact of the other roll.
 14. The assembly of claim 13 wherein each roll increases and then decreases in diameter.
 15. The assembly of claim 14 wherein each roll is of a stepped construction and each line of contact being disposed on a step.
 16. The assembly of claim 15 wherein the rolls are of identical stepped construction, and each roll having alternate steps with no lines of contact thereon.
 17. The assembly of claim 15 wherein the rolls are of complementary stepped construction and a line of contact being on each step.
 18. The assembly of claim 14 wherein means are provided for heating the stretch half and cooling the relaxation half of each roll.
 19. The assembly of claim 14 including temperature control means for adjusting the temperature of at least a portion of at least one roll.
 20. The assembly of claim 12 wherein said shafts are skewed at an angle of about 3 to 7 degrees with respect to each other. 